I. Field of the Invention
The present invention relates generally to distributor assemblies for internal combustion engines and, more particularly, to such a distributor assembly with air density compensation means.
II. Description of the Prior Art
Spark ignition internal combustion engines conventionally include a distributor having a housing secured to the engine. A distributor shaft is rotatably journalled through the distributor housing and has one end coupled for rotation in synchronism with the engine crankshaft.
A distributor plate is pivotally or rotatably mounted within the interior of the housing between a first and second rotational position while make-and-break switch means are mounted onto the distributor plate. The switch means in turn cooperate with a cam or other means secured to the rotor to selectively actuate the switch means upon rotation of the distributor shaft. The rotational position of the distributor plate is conventionally controlled by a vacuum advance connected to the intake manifold vacuum of the engine.
The previously known rotatable distributor plate in conjunction with the intake manifold vacuum control effectively advances or retards the spark in response to the intake manifold vacuum of the engine which is indicative of engine load and speed conditions. These previously known engine distributor assemblies, however, include no provision whatsoever for controlling the spark advance or retardation for the engine combustion in response to the density of the incoming air to the engine. The density of the air, which of course is dependent upon the temperature, pressure and moisture content of the air, affects the combustion charactristics o the air/fuel mixture which is supplied to the engine. Consequently, the failure of these previously known distributor assemblies to adjust the spark advance or retardation in order to accommodate varying air densities has resulted in improper combustion, which in turn, results in increased air pollution and fuel wastage.